The present invention relates to a new and improved construction of gas-blast switch.
Generally speaking, the gas-blast switch of the present development is of the type comprising a movable contact element and a stationary or fixed contact element. A blast nozzle connected with a pump chamber which can be pressurized during the course of the cut-off stroke of the gas-blast switch is operatively associated with one of the contact elements. Such blast nozzle surrounds the related contact element and its nozzle chamber has an inlet space converging towards the nozzle throat and an outlet space diverging away from the nozzle throat. In the blast nozzle there are formed channels which flow communicate with the pump chamber. These channels open at an angle with respect to the nozzle axis into the nozzle space or chamber.
Such type gas-blast switches are known, for instance, from German Patent Publication No. 2,710,868 and U.S. Pat. No. 3,946,180. The channels formed in the blast nozzle and flow communicating with the pump chamber and opening at an angle with respect to the nozzle axis into the pump chamber are assigned the task of producing a transverse blowing of the cut-off arc burning in the nozzle chamber in addition to the axial blowing of the arc which is accomplished during the cutoff stroke of the gas-blast switch. This affords an efficient cooling of the arc, particularly at the region of the throat of the blast nozzle. This improved cooling also contributes to preventing any "clogging" of the blast nozzle by heated arc plasma, which, in turn, appreciably impairs the axial blowing of the arc.
With the heretofore known gas-blast switches of this type, the channels are formed by bores which are machined or otherwise formed to extend through the nozzle body and ultimately open at the region of the nozzle throat or also shortly before such nozzle throat or thereafter into the nozzle chamber or space. If the strived for transverse blowing of the arc should be adequately effective, then there must be provided for this purpose also a sufficient quantity of extinguishing gas. However, in order to propel an adequate quantity of extinguishing gas through the bores of the blast nozzle of the heretofore known gas-blast switches, it is necessary to provide a large number of bores and/or the volume of the pump chamber and the drive which pressurizes the same must be correspondingly largely dimensioned, because the extinguishing gas, during such time as it flows through the bores, loses an appreciable part of its kinetic energy. This is particularly so in those instances, as taught in U.S. Pat. No. 3,946,180, where the bores have an angled extent or course of travel.